Euclid of Alexandria

Let it be granted that a straight line may be drawn from any one point to any other point.

Let it be granted that a finite straight line may be produced to any length in a straight line.

Let it be granted that a circle may be described with any center and any radius.

Let it be granted that all right angles are equal to one another.

And that, if a straight line falling on two straight lines make the interior angles on the same side less than two right angles, the two straight lines, if produced indefinitely, meet on that side on which are the angles less than the two right angles.

A plane angle is the inclination to one another of two lines in a plane which meet one another and do not lie in a straight line.

And when the lines containing the angle are straight, the angle is called rectilinear.

For the sake of brevity, I have omitted many things which are obvious.

The knowledge of which is useful for many things.

Let no one ignorant of geometry enter here.

The art of reasoning is the art of drawing conclusions from premises.

Geometry is knowledge of the eternally existent.

The principles of geometry are not to be disputed, but to be understood.

Mathematics is the alphabet of the gods.

The study of mathematics is like the ascent of a mountain, where the higher one goes, the wider the view.

Truth is the daughter of time, not of authority.

Give me a firm spot on which to stand, and I will move the earth.

The beautiful is in the useful.

The shortest distance between two points is a straight line.

To understand is to perceive patterns.